The black color of a soil comes from the humus or organic matter in the soil. Soil with about 5% or more organic content is black. If you can get black soil for free, that's one thing. If you have to pay for it, adding that 5% organic matter to your own soil is usually cheaper.

Anything that rots generally turns black. My pure organic compost soil is black. Worms digest organic matter in soil and what they excrete is black. I would assume the soil you are getting is good but I would still ask where it comes from. Good black organic soil that you can put your hands in up to your elbows is the best there is for roses.

I remembered that top soil is black. Am I mistaken to think top soil doesnt have much in the way of nutrients?
Yeah, i will call tomorrow and ask him where excatly it comes from. I believe my husband said it comes from a farmers field.

You would have to get a soil test to see what the nutrient levels are. Soils with 3-5% organic matter and at least 10% clay will retain nutrients, unless the soil has been cropped heavily without fertilizing.

Soil scientists classify soils with various names ("clay", "silt", "loam", etc.) "Muck" soils are naturally high in organic matter and muck soils are naturally black. (Parts of the farming regions near Syracuse, NY have muck soils.)

The soils of Hawaii are also often black, but that is because they are so volcanic.

I remembered that top soil is black. Am I mistaken to think top soil doesnt have much in the way of nutrients?

While it can indeed be black, topsoil is not necessarily black. Topsoil is the soil in which most biological activity takes place. Often it's brown (which is what I grew up with outside of Philadelphia), but it can be red if it's high in clay ("clay topsoil", like my grandmother dealt with in New Jersey), or yellow-white if it's high in sand ("sand" topsoil), or even white if it's high in limestone and therefore chalky ("chalk" topsoil).

Topsoils are a complex amalgam of the underlying rock from which they're formed (the "parent rock"), the rotted organic matter that has grown upon them and from them, and the water with which the rock and organic matter have interacted (plus the animals, plants, and microorganisms that have lived, died, and rotted in this complicated matrix). Some topsoils are indeed bereft of nutrients (sand topsoils are often that way), but other topsoils are very nutrient-rich indeed!

The topsoils of the American prairies were often very rich.

We stopped in to see our old house we had built in 1970 in Pekin, IL this weekend. A very nice cop lives there now. Gone is my 60X80' veggie garden and roses by the back stoop. It is a dog run now. Big dog!

A brook still lines the property, but is now covered by a culvert. No sign of the thousands of daffys we had planted.

That was the blackest dirt I ever had the pleasure to grow stuff in. River bottom muck is good stuff.

Now I have potters clay but tons of horse doody (sawdust horse stall stuff) and a heavy leaf mulch each year has at least made the soil tillable.

We do have some onion fields by the Muddassippi, where the soil looks black to me.

I will take a pass on the flood stuff.

D-

Here is a link that might be useful: Muck soil